There have been various curable resins used for bonding and linking. The mode of curing differs depending on the molecular constitution of resins, and the curable resins are used in different ways depending on the mode of curing such as thermosetting and reactive setting by making contact with a catalyst, moisture in the atmosphere and the like. Generally used adhesives and sealing materials take advantage of cold-setting resins, and the application mode and method of use are devised so as to start a curing reaction at the time of use. For example, the moisture-setting resin is supplied in a hermetical vessel shielded from the environment, and its curing reaction takes place due to contact with the atmosphere. On the other hand, adhesives in which curing is readily progressed due to contact between components are provided as a two-liquid type preparation so as to separate the components to one another.
A resin having a silicon-containing characteristic group such as hydrolyzable silyl groups has been developed for use as a moisture-setting resin from the view point of curing by a reaction with the moisture in the atmosphere.
For example, Japanese Patent Application Laid-Open No. H11-1635 discloses the use of a resin having hydrolyzable silyl groups as a curable resin for a moisture-setting powdery paint. The powdery paint contains a thermal latent catalyst for enhancing a hydrolysis reaction by heating, and a coating film is formed by curing as the powdery curable resin is melted by heating. Accordingly, the resin is stably preserved at room temperature without any reactions. A slush forming material employing the same mechanism as described above is disclosed in Japanese Patent Application Laid-Open No. 11-228833. In this publication document, a resin composition containing a powdery thermoplastic polyurethane resin treated with a hydrolyzable silane compound on the surface and a thermal latent catalyst for enhancing a hydrolysis reaction of the silyl group at a given temperature is molded in a heated mold to permit surface cross-linking to progress by melting of the powder and moisture.
On the other hand, it is attempted to use a resin having a hydrolyzable silyl group as a cold-setting adhesive or a curable resin for sealing materials. In this case, the curable resin is in a liquid state at room temperature, and is cured by accelerating the hydrolysis reaction with moisture in the atmosphere.
When the curable resin having a silicon-containing characteristic group such as hydrolyzable silyl groups is used for the cold-setting resins as described above, organic tin compounds such as dibutyl tin dilaurate and dibutyl tin diacetate are frequently used as curing catalysts. In particular, when a silylated urethane resin as described in Japanese Patent Publication No. 3030020 is used as a curable resin having a silicon-containing characteristic group, a curable resin composition having a relatively rapid curing speed may be obtained by blending the organic tin compound.
Other known curing catalysts for the curable resin having a silicon-containing characteristic group other than the organic tin compound include organic acids and amine compounds.
The curing rate of conventional adhesives and sealing materials using the curable resins having the silicon-containing characteristic group as described above is slow. Therefore, an improvement for enhancing the curing speed has been attempted in order to comply with the need of markets where more rapid curing is desired.
However, other problems occur by blending a large quantity of the organic tin compound as the curing catalyst for enhancing the curing speed, such that storage stability decreases, and that the resin becomes more dangerous and toxic due to an increased amount of the tin compound as a heavy metal compound. Also, when the curable resin is used as the adhesive or sealing material for plastics having hydrolyzable groups such as polyurethane resins and polyester resins, it is difficult to blend a large quantity of the organic tin compound since the organic tin compound blended in the curable resin may degrade the plastics.
The curing speed of the curing resin having a silicon-containing characteristic group is still slow when the organic acid or amine is used as the curing catalyst. Accordingly, the organic acid and amine are practically used as co-catalysts.
The object of the invention for solving the problems above is to provide a curable resin composition that is cured at room temperature with a quite high curing speed, using a curable resin having a silicon-containing characteristic group, and to provide a moisture-setting adhesive composition using the curable resin composition.